The present invention relates generally to novel and improved electro-pneumatic railroad train brakes, and more particularly to microprocessor controlled electro-pneumatic brakes with a train monitoring system.
Pneumatic train braking systems have been used in the railway industry for over 120 years. Electronically controlled, or electro-pneumatic ("E-P") brakes have also been available in the recent past. However, these E-P brakes have primarily been used only on shorter trains, such as commuter and passenger trains. Such applications have generally included only solenoid valves on the cars, activated directly by full voltage signal-power from the locomotive. However, this control method is impractical for very long trains which may possibly have over a hundred cars and reach over 13,000 feet in length. The tremendous amounts of current required to ensure that the braking system activates for the cars near the rear end of the train would be prohibitive.
Many of the E-P brakes, in their most recent development, are controlled by computers. In these modern braking systems, the computer receives various input data, performs the necessary calculations, and finally applies the brakes in the manner dictated by the program. In all electro-pneumatic and standard pneumatic braking schemes currently in use, the brakes are first applied at the locomotive. In today's automatic air brakes, after the braking action is initiated in the locomotive, air pressure in a pipe running the length of the train is reduced. This causes the control valve on each vehicle to supply air from the vehicle reservoir to the brake cylinder, ultimately applying the brakes in the vehicle. This method of braking is little changed since the first pneumatic brake was invented.
The disadvantage in this classic braking system is that the last vehicle in the train has its brakes applied last due to the time it takes for the pressure change in the pipe to travel the distance to the vehicle. Therefore, the time from when braking is desired to the time when the brakes are actually applied increases as train length increases. For long trains, the application of the brake and the actual braking action may trail each other by as much as 90 seconds. In a train traveling 60 to 70 miles per hour, this could potentially translate into 9000 feet of travel before full braking is achieved.
Another disadvantage in current railway train design is that the engineer has no access to critical operating data from other vehicles in the train. The computers used in modern E-P braking systems have very little functionality beyond applying the brakes and other brake associated tasks. These computers, in general, receive inputs of pressure measurements, or operating conditions of the pressure system, or other brake system data that is obtained locally in the locomotive. However, no data is available to the computer from the other vehicles which may be attached to the train.
It is therefore an object of this invention to provide a system whereby train braking is achieved virtually instantaneously and simultaneously throughout the train, without incurring the time lag from application of the brake to actual braking. Another object of the invention is to provide the E-P computer system with data concerning the operating conditions of other vehicles on the train.